1. Field of the Invention
The present invention relates to a separate air-conditioner for use in a room which includes a heat exchanger, an upper air fan for taking air from the room through the heat exchanger and blowing it out from the top of the room unit, and of a lower air fan for taking the air from the room through the heat exchanger and blowing it out from the bottom of the room unit.
2. Description of the Prior Art
FIGS. 11 and 12 illustrate respectively a room unit of a prior separate air conditioner. In particular, the former shows that of a floor type, while the latter shows a fan controller disclosed in Japanese Laid-Open Publication No. 55-112947. In the figures, a unit casing 11 includes an air inlet 12 for room air located substantially at the center of the front surface, an upper air plenum 13 for the room air at the upper portion of the front surface, and a lower air plenum 14 at the lower portion of the front surface. In the unit casing 11, a heat exchanger 15 is disposed oppositely to the air inlet 12, with a upper air fan 16 disposed oppositely to the upper air plenum 13 and a lower air fan 17 disposed oppositely to the lower air plenum. The upper fan 16 includes a fan wheel 18 and a fan motor 19 for driving the fan wheel 18, which is adapted to direct the room air from the air inlet 12 toward the heat exchanger 15, and blow the air out through the upper air plenum 13. The lower air fan 17 includes a fan wheel 20 and a fan motor 21 for driving the fan wheel 20, which is adapted to direct the room air from the air inlet 12 through the heat exchanger 15 and the lower air plenum into the room. A double thermostat operable at room temperature includes a thermostat 23 having a first working temperature and a thermostat 24 having a second working temperature. The thermostat 23 turns on/off the fan motor 19 of the upper fan 16, while the thermostat 24 turns on/off the fan motor 21 of the lower fan 17. An AC power source is connected to the fan motors 19, 21 via the double thermostat 22.
In operation, when the room temperature reaches the first working temperature, the thermostat 23 is operated to close its contact so that, the fan motor 19 starts to rotate, causing the upper fan 16 to direct the room air from the air inlet 12 through the heat exchanger 15 and the upper air plenum 13 into the room.
When the room temperature rises to the second working temperature, the thermostat 24 is operated to close its contact so that, the fan motor 21 starts to rotate, causing the lower fan 17 to direct the room air from the air inlet 12 through the heat exchanger 15 and the lower air plenum 14 into the room.
The conventional air conditioners, however, suffer from the following problems.
The conventional separate air conditioners are adapted, as described above, to start the upper fan when the room temperature reaches the first working temperature while the lower one when the room temperature reaches the second working temperature which is higher than the first one. Accordingly, 1) an uncomfortable draft occurs when the heating operation is started; 2) a proper temperature distribution is not obtained when the heating is stable and 3) it is too cold when the whole or entire air flow is reduced since the hot air is not directed to the lower foot area.